1011植物的水分关系概述.ppt

Chapter1 Water Relationship in Plant 1. 水分的作用 1.1 水的理化特性 1.2含水量及性质 组织和环境 自由水束缚水 自由水束缚水 1.3 水的作用 2. 细胞吸水 2.1 渗透吸水 自由能和化学势 水势 水势的度量 扩散 渗透作用 渗透势 细胞是渗透系统 质壁分离及复原 意义 细胞水势组成 压力势 衬质势 三势关系 水分移动方向 土壤植物大气 2.2 吸胀作用 2.3 代谢吸收 2.4 水孔蛋白 水孔蛋白模型 3. 根系吸水 3.1 吸水区域 3.2 主动与被动 主动吸水 吐水 渗透理论 被动吸水 3.3 内外因素 土壤有效水分 氧气土温溶液 4. 蒸腾作用 4.2 气孔蒸腾 气孔分布 气孔扩散 小孔律 气孔复合体 气孔开关学说 三学说图示 气孔外因 4.3 蒸腾内外因 内因 外因 蒸腾日变化 4.4 意义和指标 蒸腾速率 蒸腾效率系数 5. 水分运输 5.2 运输动力 5.3 运输速率 6 灌水形态指标 6.2 生理指标 水分临界期 6.3灌溉方式及WUE 3.2 Water absorption by root Active absorption: Water is pushed up by root(根压) pressure. It is a physiological phenomenon of root. Passive absorption: Water is driven up by leaf transpiration. It is a physical phenomenon of nature. Measuring — a phenomenon that the sap flows out from the wounded (cut) part — bleeding sap. Power: root pressure, 0.1-0.2MPa Phenomenon: bleeding and Guttation Characteristic: minor way, active process, energy needed Theory: osmosis theory 3.2.1 Active uptake of water Bleeding Measuring Bleeding (伤流) Guttation 吐水— leaves secrete sap from the tip or margin. ? Environmental conditions: soil water enough, air warm, higher relative humidity, often in the early morning. ? An index for healthy seedlings. How does root pressure occur? Power: Transpiration pull (蒸腾拉力). Water is pulled up along xylem vessel by a gradient of water potentials due to transpiration, ~ 30MPa. Phenomenon: branches uptake water by without root. Characteristic: main way, passive process, energy no need, Independent of root metabolism. Theory: Transpiration-cohesion-tension theory. (蒸腾－内聚力－张力学说) 3.2.2 Passive uptake of water 3.3 Factors affecting water absorption by root Inner factors： root development degree, physiological status, plant types... Outer factors: air factors: indirectly soil factors: directly (1) Soil available water (土壤有效水） Wilting coefficient(萎蔫系数) is a soil water content (%) under which plant will occur wilting permanently. Outer factors: wilting Temporary wilti